Technical Field
The present invention relates to a method of manufacturing a semiconductor device.
Background Art
Semiconductor devices include semiconductor chips on which IGBTs (insulated gate bipolar transistors), FWDs (free-wheeling diodes), or the like are formed, and are widely used as power conversion devices and the like. This kind of semiconductor chip is obtained by individually dividing a semiconductor substrate on which semiconductor elements have been formed. In addition, electrodes of the semiconductor elements on the front surface side of the semiconductor chip are bonded to external terminals via solder. Thus, a metal layer with good solder wettability (a nickel layer, for example) is formed via plating on the electrodes (see Patent Document 1, for example).
When a metal layer (plating layer) is formed via plating on the front surface (device surface) side of the semiconductor substrate, the plating solution may spread to the rear surface of the semiconductor substrate. As a result, the plating layer that was deposited on the rear surface of the semiconductor substrate will detach and mix with the plating solution inside the plating tank. This plating layer in the plating solution becomes a nucleus upon which plating material deposits, and thus the concentration of plating material within the plating solution decreases.
In addition, in order to decrease energy loss and increase heat dissipation in power devices, technology has been proposed in which the semiconductor substrate is made thinner. However, when the thickness of a semiconductor wafer with a diameter of 6 inches is decreased to approximately 100 μm, for example, problems such as cracking and warping of the semiconductor substrate occur.
Therefore, methods of manufacturing have been proposed in which the semiconductor substrate is supported by providing a support plate via an adhesive layer to the rear surface of the semiconductor substrate (see Patent Documents 2 and 3, for example). Through this method, by providing a support plate on the rear surface of the semiconductor substrate, warping of the front surface of the semiconductor substrate can be corrected. When plating a semiconductor substrate supported by a support plate in this manner, it is possible to prevent the plating solution from spreading to the rear surface of the semiconductor substrate and form a plating layer on only the front surface side of the semiconductor element.